GreenCalculus API

GreenCalculus is the emission-factor layer you do not have to build or maintain. One API serves 16,673 sourced factors spanning grid electricity, fuels, freight, refrigerants, AFOLU, CBAM, construction and spend-based EEIO, across 151 countries and mapped to 132 standards. Every value comes back with the exact source cell it was read from, the publisher licence, and the published uncertainty, so a person can cite it and a machine can trust it. Seven calculation engines sit on top of the corpus: GHG Protocol Scope 1, 2 and 3, PCAF financed emissions, embodied carbon to EN 15978, freight, spend-based, and business travel. Each returns the full working rather than a bare total, plus a deterministic receipt hash and the data version used, so a saved result reproduces identically years later, with or without us. When a publisher revises a number we say what changed and whether your figure still holds. Browsing the factor corpus needs no key at all and is unmetered. A free key adds 1,000 metered calls a month with no card, commercial use with attribution, and every calculation engine including PCAF. Open-source, classroom and research projects get ten times that quota. There is also an MCP server, so agents can look up and cite real factors instead of guessing at them.